Cylinder head for internal combustion engines



Jan. 14, 1964 J. BoTTGER ETAL 3,117,565v

CYLINDER READ EoR INTERNAL coMBusIIoN ENGINES Filed April 18. 1962 zzgerBY Jiri 'as WWK,

United States Patent Olice amiss Patented dan. 14, 19'54- 3,117,565CYLENDER HEAD FR INTERNAL CMBUSTGN ENGENES Josef Bottger, Prague, andJiri Klos, Koprivnice, Czechoslovakia, assignors tc Tatra, nroflnpotinik, Koprivnice, Czechoslovakia Filed Apr. 18, 1962, Ser. No.188,491 Claims priority, application Czechoslovakia dan. 18, 1951 11Claims. (Cl. 12S-41.57)

This invention relates to cylinder heads for internal combustionengines, and more particularly to a cylinder head for air-cooledhigh-power, high speed engines.

In its more specific aspects, this invention is concerned with problemsarising in air-cooled compression ignition engines of large size andoperating at very high compression ratios in which 4the bottom of thecylinder head is subjected to extreme thermal stresses. The compressionratio, and the efficiency of such engines is determined to `asignificant extent by the necessity of keeping thermal stresses belowthe limit determined by the highatemperature ultimate mechanicalstrength of the materials of construction employed.

lt is known to provide cylinder heads of such engines with turbulencechambers and pre-combustion chambers which somewhat contribute tolowering of the temperature at the cylinder head bottom. Such chambers,however, are not always desirable, and cannot be employed where fuel isdirectly injected into a combustion chamber formed within the top faceportion of the piston. In engines of the latter type, additionalchambers can be provided in the head only at a loss in volumetricefficiency, or at a loss in the efficiency of fuel use.

It is an object of the invention to provide a cylinder head for enginesof the type described which can absorb a heavy thermal load withoutexcessive mechanical Weakening of the materials of construction, andwithout compromising the design of the combustion space.

Another object is the provision of a liquid cooled cylinder head for anair-cooled internal combustion engine.

A more specific object is the provision of a liquid-cooled cylinder headwhich does not require an additional conduit system for the circulationof a liquid coolant.

With these and other objects in view, this invention in one of itsspecic aspects contemplates to provide the cylinder head of an internalcombustion engine of the above-described `type with a trough shapedcavity so that one of the opposite faces of the lid portion of thecylinder head constitutes the bottom of the trough whereas the otherface closes the top of the engine cylinder in the assembled condition ofthe cylinder head.

The head carries the usual rocker-actuated overhead valves and the fuelinjection nozzle. The valve rockers are lubricated by a continuousstream of oil, as is conventional, and the lubricating oil released fromthe rocker bearings overflows into the trough-shaped cavity of thecylinder head and thence into the crankcase. yIt continuously takes upcaloric energy from the head and dissipates it in other parts of theengine which are under lower thermal stress.

These and other features and the attendant advantages of this inventionwill be more fully appreciated as the same becomes better understood hyreference to the following detailed description of a preferredembodiment thereof when considered in connection with the accompanyingdrawing wherein:

FIG. l shows a cylinder head of the invention in section on an axialplane; and

FfG. 2 is a plan view of the head of FIG. 1.

The cylinder head of the invention consists mainly of a lid portion 1which covers the open top of the combustion space in a cylinder 2, andof an integral annular wall portion 4 which extends upwards away fromthe lid portion 1. The two portions of ythe cylinder head respectivelyconstitute the bottom and side wall of a troughshaped or substantiallyfrustum-shaped cavity.

The downwardly directed face of the lid portion 1 is apertured in theusual manner to provide two valve seats 3 for an lair intake and anexhaust valve respectively.

A central bore 7 in the lid portion 1 which extends upwardly into atubular boss 6 provides tight seating for a fuel injection nozzle in theusual manner, the nozzle itself not being shown. Ribs 8 which projectupwardly from the lid portion 1 connect fthe boss 6 with the wallportion 4 near the bottom of the trough. Fuel reaches the nozzle througha bore 18.

The lid portion 1 has its smallest thickness near the boss 6, andincreases in thickness toward the wall portion 4. The lower face of thelid portion 1 is approximately flat, whereas the upper face isapproximately spherically concave. The wall portion 4 decreases inthickness in a direction upwardly away from the lid portion 1 in such amanner that the cavity in the cylinder head flares upwardly toward itsopen top. The free rim of the wall portion 4 constitutes a reinforcedframe 5. yFins 19 on the outside of the Wall portion 4 promote coolingby ambient air.

A conduit 9 is integrally formed in the wall portion of the cylinderhead and has a slightly projecting orifice 9 in the upper half of 4thecavity. The conduit 9 extends downwardly from :the orifice 9 andcommunicates with the cr-ank case of the engine through an aligned borein the cylinder block when the cylinder head is installed. Only onecylinder 2 of the cylinder block is partly shown in the drawing since itis convention-al and not directly a part of :this invention.

An exhaust port 10 and an air inlet port 11 are provided in the cylinderhead in a basically conventional manner, iand communicate withrespective valve seats 3 in the lid portion 1. A projection 12 extendingupward into the cylinder head cavity above each valve seat 3 is providedwith a bore 13 which serves as a guide for the stem of a respectivevalve, not itself shown.

Apertured bosses 14 on the frame 5 receive the end portions ofrespective through bolts 2G (shown in FiG. 1 only) by means of which thecylinder head is normally fastened to the cylinder block, the crankcase, and other elements of the engine as is usual.

It will be understood that movement of the valves whose stemsreciprocate in the guide bores 13 is actuated by rockers mounted abovethe cylinder head and operating against the pressure valve springscoiled about the valve stems. The springs normally hold the valves inthe closed position, and the valves are opened by the rockers in timedsequence against the force of the springs. The rocker assembly is notillustrated since it is known in itself, but the threaded openings 16 inwhich it is anchored in the operative condition of the engine `are seenin FIG. 2. The rockers are actuated by valve lifter rods passing throughopenings 17.

The rockers are lubricated by a constant stream of oil. The rockers arearranged above the open top of the cavity in the cylinder head, as isapparent from the location of the lifters and the valve stems, and thelubricant is permitted to ow from the rocker assembly directly into thecavity, filling the same to the level of the orice 3 When the cavity isfilled to that level, any excess overflows continuously into the crankcase of the engine through the conduit 9, to be recirculated from there.

The lid portion l of the cylinder head is very much hotter than the wallportion 4, and the oil at the bottom of the trough-shaped cavity israpidly heated. It exnands and rises, drawing relatively cool oil to thebottom Although fresh oil is supplied from the top of the cavity, andexcess oil is drawn off from a point at or near the top of the body ofoil in the cavity, there is effective thermosyphon circulation of oil inthe cavity, and the lid portion 1 is cooled by the circulating oil. Thiscooling effect is enhanced by the surface increasing ribs 8 in thecavity since the grooves between the ribs are filled with oil. The oilalso acts as a heat transfer medium between the lid portion l and thefinned wall portion 4, but heat tlowbetween the several portions of thecylinder head is believed mainly to take place in the metal itself. SuchVinternal heat flow is favored by the confivuration of the portions ofthe head which arc thickest at their junction and taper toward the boss6 and the frame 5 respectively.

The spherically concave inner face of the lid portion 1 makes forminimum metal thickness in the center of the hd portion so as to preventdirect heat transfer from the exhaust to the intake port as far aspossible. The lidv center, which is at the highest temperature, directlytransmts its heat to the side wall for dissipation by the external n ns19, as far as the heat is not carried away by the circulating oil. Heatdissipation by the fins 19 is favored by the upwardly decreasingthickness of the wall portion 4. Proper circulation of the cooling oilis ensured by the upward flaring of the cavity side wall.

1t will be understood that the cylinder head with its valve roclrerassembly is surmounted by the usual valve gear cover so that the top ofthe cavity in the cylinder head while oren to the entry of oil, need notbe open to the atmosphere.

The cylinder head of the invention is of great rigidity because of itsshape which is similar to that of an inverted hollow frustum of a conerepresented by the wall portion Il, integrally joined to thesubstantially plate-shaped lid portion 1.

The cylinder head of the invention has been found to resist deformationbecause of the smaller thermal expansion of the outer fibers of the lidportion 1 which are directly oil cooled. The outward bulging of thecylinder lid in conventional engines operating at high pressures andtemperatures is a well known source of incomplete valve closure, and acracking of the lid face in the combustion chamber. The sharp edges ofthe recesses for the valve seats and the injection nozzle seat arevulnerable to such cracking in known compression ignition engines.Deformation, crack formation, and the resulting difliculties are safelyavoided by our invention.

Obviously, many modifications are contemplated and may be resorted to bythose skilled in the art without departing from the spirit and scope ofthe invention as hereinafter defined by the appended claims, as only apreferred embodiment thereof has been disclosed This is a continuationin part of our co-pending application Serial Number 166,663 filed onJanuary 16, 1962, now abandoned.

What we claim is:

l. A cylinder head for an air-cooled internal combus- .tion engine,comprising, in combination:

(a) a head member defining a substantially troughshaped cavity therein,said head member including a lid portion having two opposite faces, oneof said faces constituting the bottom of said cavity, and an annularwall portion extending away from said lid portion and constituting theside wall of said cavity, said cavity having an open top opposite SaidbOtOm thereof;

` (b) fastening means for attaching said head member to ,the open top f,an engine cylinder in sealing enr4 gagement of the other face of saidlid portion with said cylinder' top;

(c) mounting means for mounting a valve rocker assembly on said headmember above said open top of said cavity, whereby liquid coolantprovided to said rocker assembly flows downward into said cavity; and

(d) a conduit having an orifice in said wall portion communicating withsaid cavity, said conduit extending downwardly from said orifice foroverflow passage of said liquid coolant from said cavity into saidconduit, said orifice being adjacent said open top and spaced from saidbottom.

2. A cylinder head as set forth in claim 1, wherein sai.; one face ofsaid lid portion is concave.

3. A cylinder head as set forth in claim 2, wherein said concave face isof substantially spherical shape.

4. A cylinder head as set forth in claim l, wherein said side wall ofsaid cavity flares in a direction away from said bottom and toward theopen top ofthe cavity.

5. A cylinder head as set forth in claim l, wherein said fastening meansinclude a frame member xedly fastened to said head member, andthrough-bolt means for attaching said frame member to said enginecylinder.

6. A cylinder head as set forth in claim 1, further comprising aplurality of ribs integral with said head member and connecting saidbottom to said side wall in said cavity, said ribs defining groovestherebetween.

7. A cylinder head as set forth in claim 6, wherein said ribs extend ina direction from said bottom toward said top of said cavity, and saidgrooves are open toward the top of said cavity.

8. A cylinder head as set forth in claim l, wherein said wall portiondecreases in thickness in a direction away from said lid portion.

9. A cylinder head as set forth in claim 1, further comprisingair-cooling fins on said wall portion outside said cavity.

10. A cylinder head for an air cooled internal combustion engine,comprising, in combination:

(a) a head member defining a substantially troughshaped cavity therein,said head member including a lid portion having two opposite faces, oneof said` faces beinfT of substantially spherical concave shape andconstituting the bottom of said cavity, and an annular wall portionextending away from said lid portion and constituting the side wall ofsaid cavity, said cavity having an open top opposite said bottom thereofand flaring in a direction from said bottom toward said open top, thethickness of said wall portion decreasing in said direction;

(b) a frame member fixedly fastened to said head member;

(c) fastening means for attaching said frame member to the open top ofan engine cylinder in sealing engagement of the other face of said lidportion with said cylinder top;

(d) a plurality of ribs integral with said lid portion and said wallportion, said ribs extending from said lid portion in said cavity towardsaid open top of the cavity and defining therebetween grooves opentoward the open cavity top;

(e) air-cooling fins on said wall portion outside said cavity;

() mounting means for mounting a valve rocker assembly on said headmember above said open top of said cavity, whereby liquid coolantprovided to said rocker assembly flows downward into said cavity; and

(g) a conduit having an orice in said annular wall portion communicatingwith said cavity, said conduit extending downward from said orifice foroverflow passage of said liquid coolant from said cavity into saidconduit, said orifice being adjacent said open top and spaced from saidbottom.

11. A cylinder head as set forth in claim l further comprising aplurality of ribs integral with said head mem- References Cited in thefile of this patent berand connecting said bottom to said side Wal'l ins aid UNITED STATES PATENTS cavity, said bottom belng arcuately concave1n sald cavlty, and said wall portion decreasing in thickness in adirection 156173545 H5111 Feb' 15 1927 away from said lid portion; andair-cooling n means on 5 13393255 Nlven Dea 10, 1929 said wall portionoutside said cavity. @509,178 Van Ranst May 231 1950

1. A CYLINDER HEAD FOR AN AIR-COOLED INTERNAL COMBUSTION ENGINE,COMPRISING, IN COMBINATION: (A) A HEAD MEMBER DEFINING A SUBSTANTIALLYTROUGHSHAPED CAVITY THEREIN, SAID HEAD MEMBER INCLUDING A LID PORTIONHAVING TWO OPPOSITE FACES, ONE OF SAID FACES CONSTITUTING THE BOTTOM OFSAID CAVITY, AND AN ANNULAR WALL PORTION EXTENDING AWAY FROM SAID LIDPORTION AND CONSTITUTING THE SIDE WALL OF SAID CAVITY, SAID CAVITYHAVING AN OPEN TOP OPPOSITE SAID BOTTOM THEREOF; (B) FASTENING MEANS FORATTACHING SAID HEAD MEMBER TO THE OPEN TOP OF AN ENGINE CYLINDER INSEALING ENGAGEMENT OF THE OTHER FACE OF SAID LID PORTION WITH SAIDCYLINDER TOP; (C) MOUNTING MEANS FOR MOUNTING A VALVE ROCKER ASSEMBLY ONSAID HEAD MEMBER ABOVE SAID OPEN TOP OF SAID CAVITY, WHEREBY LIQUIDCOOLANT PROVIDED TO SAID ROCKER ASSEMBLY FLOWS DOWNWARD INTO SAIDCAVITY; AND (D) A CONDUIT HAVING AN ORIFICE IN SAID WALL PORTIONCOMMUNICATING WITH SAID CAVITY, SAID CONDUIT EXTENDING DOWNWARDLY FROMSAID ORIFICE FOR OVERFLOW PASSAGE OF SAID LIQUID COOLANT FROM SAIDCAVITY INTO SAID CONDUIT, SAID ORIFICE BEING ADJACENT SAID OPEN TOP ANDSPACED FROM SAID BOTTOM.